This invention relates to the production of glass fibers, and in particular, to winding a glass fiber strand to form packages. More particularly, this invention relates to controlling the position of the strand guide with respect to the collet for optimum package buildup.
Mineral fibers are used in a variety of products. The fibers can be used as reinforcements in products such as plastic matrices, reinforced paper and tape, and woven products. During the fiber forming and collecting process numerous fibers are bundled together as a stand. Several strands can be gathered together to form a roving used to reinforce a plastic matrix to provide structural support to products such as molded plastic products. The strands can also be woven to form a fabric, or can be collected in a random pattern as a fabric. The individual strands are formed from a collection of glass fibers, or can be comprised of fibers of other materials such as other mineral materials or organic polymer materials. A protective coating, or size, is applied to the fibers which allows them to move past each other without breaking when the fibers are collected to form a single strand. The size also improves the bond between the strands and the plastic matrix. The size may also include bonding agents which allow the fibers to stick together, thereby forming an integral strand. It is to be understood that the use of a size is optional.
Typically, continuous fibers, such as glass fibers, are mechanically pulled from a feeder of molten glass. The feeder has a bottom plate, or bushing, which has anywhere from 200 to 10,000 orifices. In the forming process, the strand is wound around a rotating drum, or collet, to form, or build, a package. The completed package consists of a single long strand. It is preferable that the package be wound in a manner which enables the strand to be easily unwound, or paid out. It has been found that a winding pattern consisting of a series of helical courses laid on the collet builds a package which can easily be paid out. Such a helical pattern prevents adjacent loops or wraps of strand from fusing together should the strand be still wet from the application of the size material. The helical courses are wound around the collet as the package begins to build. Successive courses are laid on the outer surface of the package, continually increasing the package diameter, until the winding is completed and the package is removed from the collet.
A strand reciprocator guides the strand longitudinally back and forth across the outer surface of the package to lay each successive course. A known strand reciprocator is the spiral wire type strand oscillator. It consists of a rotating shaft containing two outboard wires approximating a spiral configuration. The spiral wires strike the advancing strand and direct it back and forth along the outer surface of the package. The shaft is also moved longitudinally so that the rotating spiral wires are traversed across the package surface to lay the strand on the package surface. While building the package, the spiral wire strand oscillator does not contact the package surface. Although the spiral wire strand oscillator produces a package that can be easily paid out, the package does not have square edges.
A known strand reciprocator which produces square edged, cylindrical packages includes a cam having a helical groove, a cam follower which is disposed within the groove and a strand guide attached to the cam follower. As the cam is rotated, the cam follower and strand guide move the strand longitudinally back and forth across the outer surface of the rotating package to lay each successive course. A rotatable cylindrical member, or roller bail, contacts the outer surface of the package as it is being built to hold the strand laid in the latest course in place at the package edges as the strand guide changes direction. The roller bail is mounted for rotation, and bearings are used to reduce the friction between the roller bail and the mounting surface. The collet and package are rotating at high speeds during winding. The contact between the roller bail and the rotating package surface causes the roller bail to rotate, and the speed of the roller bail surface is generally equal to the high rotational speed of the package surface. The roller bail has a fixed diameter which is generally less than the diameter of the collet, and may be only 10% of the collet diameter. Therefore, the roller bail must rotate at higher revolutions per minute (RPMs) to keep the roller bail surface traveling at the same speed as the speed of the package surface. To operate effectively throughout the preferred range of package sizes and preferred collet speeds during winding the roller bail may have to rotate at 70,000 RPMs or higher.
The rotating rollers of the roller bails contact the strand as it is laid on the package surface. If the speed of the roller bail surface does not match the speed of the package surface, the roller bail will apply abrasive forces against the strand, and this can break some of the fibers in the strand. Bearings are provided between the roller bail mounts and the rotating roller bail to reduce friction and allow the roller bail to rotate at high RPMs. Typical grease lubricated bearings which have been used in the past have been found not to reduce the friction enough to allow the roller bails to operate at such high RPMs without causing abrasive forces against the strand which can break strand fibers. The strand reciprocator has other moving parts in addition to the roller bails with surfaces which need lubrication. The rotating cam has bearings which use lubrication. The cam follower needs lubrication while it moves along the groove on the cam surface.
Several attempts have been made to control the strand guide or guide eye position during package buildup. For example, U.S. Pat. No. 3,854,668 to Rudd appears to disclose a yam winder that establishes an absolute position by moving the guide eye into contact with the collet and then zeroing out a potentiometer.
U.S. Pat. No. 4,715,548 to Miyake et al. appears to disclose a winding process in which a controller 8 computes the diameter of the package during the winding process, using the rotational speed of the package and the input signal from the inverter to the motor.
U.S. Pat. No. 3,365,145 to Klink et al. appears to disclose a winder that maintains the guide eye close to the package, but backs off the guide eye in response to the increased size of the package. The backing off is effected with a spring 92 connected via a microswitch 96 to a backoff motor 96.
It has been found that a lack of control of the strand guide position with respect to the collet poses several problems, including but not limited to, partial break out of filaments at the bushing, a bushing tension increase, a potential mechanical failure on the turret system or collet spindle, a worn or damaged strand guide assembly, and lubrication failures. Thus, it would be desirable to control the relative position of the strand guide with respect to the collet and to monitor the force applied to the package by the strand guide during the packaging process.
This invention relates to a method of controlling the position of the strand guide during package buildup, the method comprises the steps of:
rotating a collet for building a package;
rotating a cam having a strand guide for winding a strand on the rotating collet;
moving the rotating cam radially toward the rotating collet until the strand guide contacts the rotating collet;
monitoring a torque on the collet as the strand guide contacts the collet; and
moving the rotating cam radially away from the rotating collet until a desired torque on the collet is reached.
In an alternative method of the invention, the method comprises the steps of:
rotating a collet for building a package;
rotating a cam having a strand guide for winding a strand on the rotating collet;
moving the rotating cam with a receder toward the rotating collet until the strand guide contacts the rotating collet;
determining a torque on one of the collet, the cam and the receder as the strand guide contacts the collet; and
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.